News

Relating taxonomy-based traits of macroinvertebrates with river sediment quality based on Basic and Zero-Inflated Poisson models

Due to growing anthropogenic stress on aquatic ecosystems it is important to have accurate and fast methods for environmental risk assessment. Ecological assessment of freshwaters is traditionally based on the diversity approach where diversity decreases with increasing environmental disturbance. In this paper, we propose a novel approach where modelled changes in trait composition of macroinvertebrates are used to assess the river sediment quality. We hypothesized that the trait composition, in this case the body length of the organisms, would change as metal concentrations increase. We found that the abundance of macroinvertebrate taxa decreased at almost all body lengths with a decreasing quality of the metal contaminated river sediment. It was also found that the number of different body lengths decreased with increasing metal pollution, indicating a decrease in diversity of the macroinvertebrate community. Smaller organisms seemed to be more resistant to metal pollution. This research showed that trait-based ecological risk assessment has high potential, but that possibly other traits besides body length should be included to strengthen our conclusions.

Hard X-ray nanoprobe investigations of the subtissue metal distributions within Daphnia magna

To improve our capacity to evaluate the impact of metals on aquatic organisms, the fundamental processes of uptake, elimination and detoxification need to be fully understood. To this end, the freshwater crustacean Daphnia magna has long served as a model organism for studying whole body bio-accumulation. In order to fully comprehend the active regulation of internal concentrations within aquatic biota, the toxicological research needs to move from the microscopic tissue scale towards a (sub)cellular field of view. We developped a novel sample preparation technique which, when coupled to advanced elemental imaging, reveals the distributions of Ca, Fe and Zn within D. magna at the subtissue level. The presented technique was found to be well suited for trace-level bio-imaging which may ultimately aid in the discovery of new insights in the detoxification processes within aquatic model organisms.

The Combined Effect of Dissolved Organic Carbon and Salinity on the Bioaccumulation of Copper in Marine Mussel Larvae 

Due to natural and anthropogenic influences, copper concentrations can be elevated in the aquatic environment. However, the total dissolved Cu concentration is, by itself, an inefficient predictor of copper toxicity. Considerable efforts have been made to improve the prediction of toxic effects by taking into account the aquatic concentration of other elements and dissolved organic carbon (DOC). These models are based on Cu accumulation at a so-called biotic ligand somewhere in the exposed organism. Mussels, and especially the larvae, are very sensitive to copper. Because of their ecological and economical importance, more specific knowledge about the influence of salinity and DOC on Cu accumulation and distribution in mussel larvae was needed. By collaborating with the X-ray microscopy and imaging group of the UGent (XMI), we could use

An approach to assess the regulatory relevance of micro-evolutionary effects in ecological risk assessment of chemicals: A case-study with Cd

Through ecological risk assessment (ERA) policy makers try to set protective norms for harmful chemicals in the environment. Typically, such ERAs are based on ecotoxicological research performed in the lab. However, these laboratory conditions tend to lack some measure of realism compared to the actual situation in the environment. For instance, usually only one particular individual of a species is considered in ecotoxicological tests, while in the environment multiple, different individuals are present. As with us, humans, some of these individuals can cope better with a certain chemical in the environment than others. Under continuous presence of such a chemical these, more tolerant, individuals will survive and reproduce, while the other individuals will perish. Overall, the group of individuals will become more tolerant to the chemical, a process which is called micro-evolution. In this most recent paper an approach is suggested to take this micro-evolutionary processes into account in ERA to, ultimately, make our risk assessment of chemicals in the environment more realistic.